Propeller control mechanism



June 23, 1953 Filed June 10, 1948 E. MARTIN I-:TAL`

PROPELLER CONTROL MECHANISM 5 Sheets-Sheet l INVENTORS EvZeMa 'Zaze fmw" June 23, 1953 E. MARTIN ETAL PROPELLER CONTROL MECHANISM 3 Sheets-Sheet 2 Filed June 10, 1948 i mi@ n may y WMM w Q mi@ Ew Nmw QQ @v MB t June 23, 1953 E, MARTlN ET AL 2,643,077

PROPELLER CONTROL MECHANISM Filed June 10, 1948 3 Sheets-Sheet 5 Patented June 23, 1953 PROPELLER CONTROL MECHANISM Erle Martin, West Hartford, and Calvin D. McCarthy, Manchester, Conn., assignors to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application June 10, 194.8, Serial No. 32,244 claims. (o1. 244-134) This invention relates to hydraulically controllable propellers and particularly to propellers of this type which may be feathered or reversed and to improved control mechanism operative during unfeathering and unreversing of the propeller blades.

In propellers having pitch changing means capable of turning the blade beyond the normal operative range, in which the `pitch angle is usually automatically controlled by governor. into eX- treme or special purpose ranges such as feathered or reverse pitch positions, it is usual to operate the propeller blades in the normal range by a relatively low iiuid pressure which is adequate to overcome the aerodynamic and centrifugal twisting moments exerted against these blades in this range. The blades are usually moved into and out of the extreme positions thereof by a higher fluid pressure to which the propeller pitch changing mechanism is subjected only while the propeller is in or being changed to or from these extreme special purpose ranges.

It is an object of this invention to provide improved means for controlling admission of the higher pressure fluid (hereinafter referred to as the high pressure fluid) to the propeller.

Another object of the invention is to provide improved means operative during unfeathering and unreversing for automatically interrupting the source of high pressure iluid to the propeller pitch changing mechanism when the propeller has returned to the governor controlled constant speed and range.

A further object of the invention is to provide means for interrupting the propeller electrical deicing system while the propeller pitch changing mechanism is being changed to or from the extreme special purpose positions of feather or reverse pitch.

A still further object of the invention is generally to improve the construction and operation of governor controlled pitch changing propellers.

These and other objects and advantages of the invention will be apparent from the specification and claims and from the accompanying drawings which illustrate what is now considered to be the preferred embodiment of the invention.

l'n the drawings;

Fig. l is a diagrammatic longitudinal section through a propeller hub constructed according to the invention.

Fig. 2 is an enlarged showing or" a portion of Fig. 1 illustrating the brush and slip ring at the blade end.

Fig. 3 is a longitudinal section through a propeller hub similar to Fig. 1 showing an alternate construction of theinvention.

Fig. 4, section 4 4 of Fig 3.

Fig. 5 is a diagrammatic view showing the propeller hub, the constant speed control means and associated control apparatus for feathering, unfeathering, reversing and unreversing the propeller with the parts shown in the position assumed during constant speed operation, on speed condition, the constant speed control means and the propeller hub being shown in section.

Fig. 6 isa view of the shank end of the propeller blade showing the position of the control slip ring with respect to the blade.

Fig. 7 is a diagrammatic view showing the portion of control apparatus of Fig. 5 used during reversing with the parts shown in the first position assumed as reversing switch is operated.

Fig. 8 is Fig. '7 showing the parts in the position immediately following the action shown in Fig. '7.

Fig. 9 is Fig. 7 showing the parts in the position assumed upon the completion of reversing with the propeller in the reverse pitch position.

Fig. l diagrammatically illustrates the principal elements of the improved controllable pitch feathering and reversing type propeller. Such a propeller `as generally indicated at I0 normally comprises a hub portion I2 mounted by longitudinal splines on propeller shaft I4 and provided with a plurality of blade receiving sockets such as the one indicated at I6. The propeller may have a plurality of blades mounted one in each socket, the blade for socket I6 being indicated at I8. The blades .are so mounted as to be rotatable about the longitudinal axis in pitch changing directions and may be retained in the sockets by suitable antifriction bearings, not illustrated, interposed between a socket abutment and a liange 20 on the blade end in a manner well known to the art. Each blade is provided on its end within the hub member I2 with a gear sector as indicated at 22 for blade I8, .all of lwhich gear sectors mesh with a master gear 24 supported by the hub I 2 and rotatable about the longitudinal axis of the hub. Gear 24 is mounted on a rotatable member 2S rotated through a cam and follower mechanism, including movable cam 28, cam rollers30 and lxed cam 32, by a piston 34 reciprocable in a cylinder 35 connected to 4the front end of hub i2 and having uid connections to the opposite ends thereof as will be described later. Themovable cam slots, as generally indicated at 38, have a substantially straight intermediate portion 40 for constant speed control, a steep pitch portion 42 at the high pitch end for feathering the propeller, and a steep pitch portion 44 at the low pitch end for reversing the propeller. The cam slots 46 of the stationary cam 32 are similarly designed but slope in the opposite direction.

The propeller may be provided with an electrical deicing system for preventing the form-a.- tion of ice or removing ice from the blades which may accumulate during operations under icing conditions. The deicing system generally consists of a blade heating element 48 mounted on the leading edge of the blade I8, a deicing relay 69 and a deicing timer 384 (Fig. 5). The heating element 48 is connected by conductor 50 to a blade deicing slip ring 52. A b rush 54 carried by suitable insulating means in a housing and bracket 56 which is mounted on hub blade receiving socket I6, forms a sliding contact with blade deicing slip ring 52 and is connected `with propeller deicing slip ring 58 by conductor 59. Propeller deicing slip rings 58 and 6|) are secured to the propeller hub I2 for rotation therewith. Slip ring 66 forms the .ground connection for propeller deicing as well as for the contact slip ring 262, the latter will be described later. Brushes 62 and 64 are mounted by suitable insulation in brush housing 66 Aand form wiping contact with slip rings 58 and 68, respectively. Brush housing 66 is nonrotatably secured to the engine 68. Brush 64 is connected to the ground at a suitable place in the airplane and 'brush 62 is connected to the deicing relay 69 (see Fig. 5) by conductor 18. Electrical energy for operating the blade heating elements in supplied to the deicing relay 69 from a suitable source, such as a battery |62. A deicing timer 394, supplied with electrical energy from battery |62, for actuating the deicing relay 69 and is connected thereto by conductor 396, switch 2 I1 of relay switch of 398 and conductor 298, A control slip ring, generally indicated at 262, is provided on the butt end of the blade I8 inside propellfil` hub I2. This control slip ring 262 (Fig. 6) is provided with two insulated segments 346 and 354. The remainder of the slip ring, segments 348 and 268, is electrically conducting to the propeller blade. Insulating segment 346 corresponds to the reverse pitch range of the propeller blade plus a few degrees in the low pitch range. Insulating segment 354 is near the high pitch end of the constant speed range. A brush 356 is carried by an insulating housing 358 which is secured in the propeller hub I2 and is held in contact with slip ring 262 by a compression spring 360. Conductor 364 connects brush 356 through spring 360 with slip ring 366 which is rotatably secured with proper insulation to propeller hub I2. A brush 368 which forms a wiping contact with slip ring 366 is mounted in suitable insulation and carried by nonrotatable housing 66. Conductor 256 which returns from brush 368 connects with the unreversing and unfeathering circuit as shown in Figs. 5, '1, 8 and 9.

An alternate method of construction that may be used in lieu of the previously described contact slip ring is shown in Figs. 3 and 4. It consists of a cam 318, secured to blade I8, having two raised segments 312 and 314 which correspond to insulating segments 346 and 354 respectively of contact slip ring 262. Cam 318 has the same position relative to the blade chord center line as has slip ring 262. Switch 316, mounted on bracket 56, consists of a'pllln'ger 01 Cam follower 318 and is held in contact with cam 318 by compression spring 380. A bridging contact 382 is secured to plunger 818. When plunger 318 is in contact with the raised segments 312 or 314 bridging member 382 is out of contact with contacts 384 and 386. When plunger 318 is between the raised cam segments or riding in the cam depressions, bridging member 382 will form a circuit with conductor 256, brush 368, slip ring 366, conductor 888, contact 384, bridging member 382, contact 386 which returns to ground in the propeller.

' Still another method of providing a control means for stopping unfeathering and unreversing can be accomplished by forming blade decing slip ring 52 (Fig. l) with an insulated portion identical in length of arc and position to Segment 346 of control slip ring 262. It will be connected to the unfeathering and unreversing electrical circuit conductor 256 through slip ring 58, brush 62 and conductor 16 and control slip ring 262 and its associated mechanism will be omitted.

A shaft I4 is rotatable in an oil sealed bearing 12 (Fig. 5') having two external fluid connections 14 and 16 leading from the governor mechanism generally indicated at 18. The connection 14 leads through radial ports to a channel 8!) extending outboard through a member 82 which is an extension of shaft I4. An annular piston 34 in cylinder 36 has a tubular hub extension 9B mounted for reciprocation on shaft extension 82. Connection 16 leads through radial ports and longitudinal channels 84 in member 82 to the exterior of member 82 through ports 86 between sealing rings 88 and 9 2 and ports 90 between rings 94 and 36. The tubular hub 98 of piston 34 is also provided with a ring of ports |00 through which fluid may pass. Fluid may also flow from channel 84 into the inboard end of cylinder 36 through one or more check valves |02 arranged to open at a relatively low pressure differential between the yfluid in channels 84 and in the space between the piston 34 and the inboard end of cylinder 3 6. Fluid at the high pressure (higher than governor control pressure) in the space inboard of the piston may flow to channel 84 through high pressure check valve |04 which prevents the ow of fluid from channel 84 to the cylinder space and also prevents the ilow of fluid from the cylinder` space to channels 84 until the fluid in the cylinder space has reached the high pressure.

When uid is supplied under governor control pressure through connection 14 the fluid will enter the space at the outboard end of cylinder 36 through channel 80 and force piston 34 inboard and fluid from the space to the rear of the piston will be drained through ports |88 and channels 84 to connection 16 which will be vented to the governor pump inlet. If the supply of fluid to the front end of the cylinder is continued the piston will move inboard until ports |88 are covered by sealing ring 92, whereupon uid will be trapped in the space to the rear of the piston and no further inboard movement of the piston can take place since the governor controlled pressure is less than the high pressure necessary to open check valve |04. The closure of port |88 by rings 82 thus constitute a low pitch hydraulic limit sto-p which predetermines the minimum pitch angle of a propeller blade as long as the propeller is functioning under governor control, When iluid under pressure is supplied to connection 16 and channels 84 the fluid will enter the space to the inboard side of the piston through low pressure valve |02 and force the piston outboard while :duid in the outboard end in the cylinder will ow out through channel and connection 14 which will be vented to the governor pump inlet.

A high pitch limit stop for the governor controlled operation of the propeller may be provided in any one of several ways known to the art as for example, by changing the slope of the cam which rotates the gear Such a change in cam slope is indicated at 42 (Fig. l) thereby increasing the resistance of the mechanism to further pitch change to such an extent that the resistance cannot be overcome by the hydraulic iiuid at governor controlled pressure, but will require the higher pressure as is applied during feathering to the operation at the rear of the piston 34.

Propeller pitch changing mechanism, therefore, operates between diiferent predetermined low and high pitch limit stops as long as the mechanism is supplied with iluidl at lower or governor controlled pressure, but the pitch may be moved beyond either of the cam limit stops by the application of hydraulic fluid at the higher pressure which is sufficient to overcome the resistance of the change in the cam slope to feather the propeller or to unseat check valve I 04 to reverse the pitch. The feathering and reverse pitch operation will be described later.

rlhe governor is shown diagrammatically in Fig. 5 to which reference is now made.V The governor comprises a rotatable shaft |08 carrying gear |55 which meshes with the gear |05 carried by the engine driven shaft I4. A flange I0 which is nxed to the upper ends of shaft |08 pivotally supports a pair of ily balls |92. The shaft |88 may be made in a single piece as shown, or if desired, may comprise several sections connected together as by splined joints.

Intermediate its ends the shaft carries a gear H4 which meshes with a gear H6 supported on a hollow axle journalled in a governor base ||'8 to form a booster pump. Hydraulic fluid is supplied to this pump from any convenient source, the source shown herein being the engine lubricating pump which is supplied through a conduit |22 from the engine oil tank or reservoir |24 and discharges through conduit |28, duct |28 and branch passage |29 to the intake of the booster pump. A relief valve |21 limits the pressure in conduit 28 and in conduit |3| leading to the engine lubricating system. Oil from the booster pump blows through check valve |30 and channel |32, through ports in a hollow shaft of |58 into annular pressure chamber |34, between annular lands |36 and |38 of a hollow piston rod of a governor pilot valve |40 which is vertically reciprocable in the hollow shaft |08 by the flyv balls H2 and a speeder spring |42 which act oppositely on a flange |43 on the piston rod. When the pilot valve |48 is forced upwardly, low pressure oil supplied by the booster pump I| 4, H5 hows from the chamber |84 through ports in the shaft |08 to channel |44 which communicates with external :duid connection-16. When the low pressure oil is connected to fluid connection 15, the connection 'i4 is connected through channel and suitable ports in shaft |08 between the lands |36 and 232 to the booster pump inlet channel |28, thus establishing a vent through relief valve |21 of conduit |3| for oil on the inboard side of the pitch changing piston 34. The results of admitting governor pressure iiuid through connection 16, as previously described, is to move the piston 34 outboard, i. e., to increase the pitch of the blades with a resultant rand conductor decrease in R.. P. M. As the governor fly balls ||2 slow down to permit the speeder spring |42 to depress the piston rod of valve |40 so that the land |36 cuts off the low pressure governor fluid passing from chamber |34 to channel |44 when the predetermined speed has been reached for which the governor is set.

If the governor speed falls below the predetermined valuey pressure fluid in chamber |54 will be admitted past the land |38 to channel |48 and external fluid connection 14 to move piston 34 towards low pitch position while the fluid on the inboard side of piston 34 will be vented through external connection 16, channel |44 and the hollow stem of pilot valve |40 into the intake channel |28 of the governor booster pump. A relief valve |48 ls provided in the governor booster pump discharge as is usual in this type of governor.

High pressure fluid is supplied to the pitchv changing mechanism in the propeller hub for moving the piston 34 beyond the intermediate constant speed range above described into the special purpose ranges in which the blades are feathered in one extreme position and reversed in pitch at the other extrem-e position thereof. To this end a high pressure pump |50 is supplied from the reservoir |24, through conduit |52 and discharges through conduit |54 into the governor base H8.

The admission of high pressure fluid from pump |50 to opposite sides of piston 84 is controlled in part by the valve mechanism already described in the propeller hub and by the governor pilot valve. A solenoid valve |58 controls the fluid pressure to the upper side of land 2|6 on the piston rod of valve |40 to position the governor valve |40 to selectively admit high pressure iiuid through either connection 14 or 18 leading to the pitch control mechanism in vthe hub. A pressure cutout switch |58 is provided for interrupting the operation of the high pressure pump |50 as will be described later. High pressure pump |50 is driven by an electrical motor energized by a battery or other suitable source of power |62, through conductor |84, switch |88 |68. The electrical apparatus controlling the operation oi switch |68 and solenoid valve |56 includes cutout switch pushpull switch |10, toggle switch |12, and solenoid switches |14, |16, |18 and |80. Switch |10 is normally biased by compression springs |82 and |84 into an intermediate switch open position in which the movable bridging contact |88 is held between and out of contact with two sets of stationary contacts, one of which set is engaged by the bridging member when the switch is pulled and the other of which is engaged when the switch is pushed. The movable contact member of solenoid switch |56 is constantly biased into open position by spring |83 while the movable contact member of cutout switch is constantly biased into the closed position by compression spring |90. Solenoid-valve |58 is constantly biased to the right as viewed in Fig. 5 by compression spring |92 while the movable switch members of solenoid switches '14., |18, |18 and |80 are biased upwardly as viewed in Fig. 5 by tension springs |94, |96, |98 and 200.

Since the supply of electrical energy in an airplane is generaly limited and the demand of the electrical deicing system and the high pressure pump |50 operating simultaneously may exceed the supply, it is found advisable to interrupt the deicing system while the high pressure pump is operating. Toaccomplish this, arelay switch 390 has beeninserted between thedeici'g timei` 384 and the deicing relay 69. Relay switch 390is normally biased upwardly'byltension spring 392 as viewed in Fig. 5. This completes the circuit between battery |62, deicing timer 384, conductor 386, switch 2|1, conductor 398 and deicing relay 69. The interruption of the electrical deici'ng is accomplished by energizing solenoid 220 of relay switch 380 which is in the same circuit as that to energize the solenoid 2|4, for actuating motor |60 to drive the high pressure pump |50. The following description includes the interruption of the deicingsystem but if the electrical energy supply of the airplane is adequate, relay switch 380k may be dispensed with and deicing can take place'simultaneously withthe operationo'f high pressure pump |50.

To operate the propeller blade into feathered position, the movable switch is pushed to compress spring |82 and bridge one set of stationary contacts 202, 204 and 206. This completes a circuit from the positive side of battery |62 through conduit 208, contact 206, movable bridging contact |86, to contact 202, through conduits 2I0, 2|2, to solenoid 2|4 of switch |66 closing the circuit to motor |60 to start the high pressure pump |50. This circuit also forms a branch circuit to de-energize the deicing system by opening switch 2|1 through conductor 2|8 for solenoid 220. The above operation of switch |10 also establishes a circuit from battery |62 through conductor 208, contact 206, movable bridging contact |86, contact 204, holdingcoil 222, ccnductors 224, 226, and contacts of switch |58.

High pressure fluid will flow fromconduit |54, opening valves 233 and 235 through channel 22S and ports in hollow shaft |08, into chamber 2|4, between larger diameter land 2|6 and smaller diameter land 232 of piston rod of valve |40, thus moving the governor' pilot val'vevupward so that high pressure fluid from conduit |54 can pass through holes 234 and channel |32 into. chamber 34 within shaft |08 and thence to channel |44 and connection 16.

As previously explained, this fluid will act with suflicient force to unseat valve |02 on the inboard side of piston 34 and also to move follow-er members 30 into the steeper special purpose range of the cam slots to feather blades I8. As piston 34 reaches the outermost position in which the blades are feathered, it reaches the limit of travel in this direction either by the engagement of followers 30 with the ends of the cam slots 38 or by engagement of special stops which may be provided for the purpose. High pressure builds up on the discharge side of pump |50 and on the inboard side of piston 34 when the piston travel is stopped. This pressure acts through passage 236 which communicates with fluid connection 16 and chamber 238 of pressure cutout switch |58 causing movable contact 240 of this switch which is carried by piston 242 to open the circuit or holding coil 222, allowing spring |82 to return switch |10 to its intermediate open switch position. This also interrupts the circuit through solenoid 2|4 resulting in stopping high pressure pump |50 with propeller blades in feathered position. The engine cannot rotate the propeller in feathered position of the blad-es and consequently the propeller and the governor will stop rotating and the blades will remain in the feathered position until unfeathered.

In order to unfeather the blades, switch |10 is pulled to compress spring |84 and move bridgingmember |86 into engagement with contacts 242, 244, 246 and 248 thus establishing a circuit from battery |62 to conductor 208, contact 248, movable bridging contact |86, contact 246, conductor 250, solenoid 252, which engages the switches of solenoid switch |14, conductors 254, 256, brush 258, and electrical conductor segment 260 of control slip ring 262. A circuit is also completed from battery |62, conductor 208, contact 248, movable bridging contact |86, contact 244, conductor 264, switch 266, conductor 2|2, solenoid 2|4 of switch |66 which closes the circuit of motor |60 to start high pressure pump |50. This circuit breaks the deicing circuit as previously described by opening switch 2|1. Still another circuit is completed from battery |62, conductor 208, contact 248, movable bridging contact |86, contact '242, conductor 268, switch 210, conductors 212, 214, solenoid 215 of valve |56.

High pressure fluid now ows from conduit |54, through holes 234 of opened valve 233 and channel 261, through valve |56, this valve now being moved to the left to permit the fluid to pass from channel 261 through channel 269 to act on the upper side of a large diameter land 2|6.` The high pressure fluid also flows as before through channel 228 into chamber 2|4 where it acts on the bottom surface of land 2|6 and also on the top surface of land 232. Since the fluid pressure on land 2|6 is balanced, the pressure on the top surface of land 232 causes pilot valve |40 to be depressed into a position such that the high pressure fluid which passes through holes 234 and channel |32 into chamber |34 is now permitted to enter the annular passage 21| which communicates with channel |46, external connection 14 leading to the outboard side of piston 34 to unfeather the blades.

-v To carry out the unfeathering operation during flight, the switch |10 is held out manually while the piston 34 moves the blades from the feathered position. As long as brush 258 remains in the contact area 260 of control slip ring 262 and switch |10 is held out manually the unfeathering operation will progress until the electrical conducting section area 260 is turned past the brush 258 breaking the circuit which will break the circuit to coil 252 of relay |14, shutting off the high pressure pump |50 and return the propeller to the governor control. At that time the switch |10 may be released as it no longer has any function.

To reverse the pitch of propeller blades |8, switch |12 is moved down, as shown in Fig. 7 and its movable bridging contact 216 is moved down to contact the stationary contacts 216 and 280. As a result the following circuits will be established: (1) A circuit from battery |62, conductors 282, 284, bridging contact 216, contact 216, conductors 286, 214, solenoid coil 215 of valve |56. (2) A circuit from battery |62, conductors 282, 284, bridging contact 216, contact 280, conductor 288, switch 290 of solenoid switch |16, conductors 292 and 294, solenoids 296, 298 of solenoid switches |18 and |80, respectively, conductors 300, 302, 226, and contacts of pressure cutout switch |58. The energizing of solenoid coils 266 and 298 bring switches 304 of solenoid switch |18 and switches 306 and 300 of solenoid switch down into contact, as viewed in Fig. '1. When solenoid switch |18 is brought down as shown in Fig. 7, the armature 3|0 of solenoid 3|2 engages the latch 3|4 of armature 3|6 and holds solenoid switch |18 in a down or contacting position. (3) A holding circuit is now formed from battery |62, conductors 282, 284, bridging member 216, contact 266, conductors 268, 3|6, switch 366, conductors 3|| and 294, solenoids 236 and 298, conductors 366, 362, 226, contact points of pressure cutout switch |58; (4) A circuit from battery |62, conductors 262, 326,322, switch 364, conductor 324 and solenoid 326. This circuit will bring solenoid switch |16 down into the position shown in Fig. 8 openingcircuit (2) as a result of opening switch 296. The holding circuit (3) now maintains switches |16 and |86 down. A circuit is now established from battery |62, conductors 262, 326, 328, switch 366, conductors 336, 332switch 334, conductor 336, and solenoid 2 I4 to close the circuit to motor |66 for driving high pressure pump |56. This circuit also interrupts the deicing circuit as previously described.

High pressure uid is now supplied from conduit |66 (Fig. 5 through holes 234 of opened valve 233, valve |56 and conduit 269 to the upper side of land 2|6. High pressure fluid also passes `through channel 228 to chamber 2|4 where it acts on the upper surface of land 232 and on the lower surface of land 2 6. Pilot valve |46 consequently moves downward to permit the high pressure fluid from chamber |34 into annular passage 21| and communicating channel |46 and external connection 14.

When the cam followers 36 have reached the inboard ends of the cam slots orwhen the reverse pitch stops are engaged, if such stops aie employed, the pressure on the outboard side of piston 36 and the conduits leading thereto builds up tothe full pressure developed by the high -i pressure pump |56. This pressure in conduit 66 is transmitted to the fluid in a channel 336 to act on the right-hand end of valve 346 and move the latter to the left admitting fluid to the chamber 236 of the pressure cutout switch |56 and cause the switch to open its contacts and interrupt the holding coil circuit for switch H36. Switch |66 will therefore move to its normal open position shown in Fig. 9 when the blades have.

reached the reversed pitch position and as a result circuits 3 and 5, previously described, which were completed by moving switch |12 downwardly will be opened.

Means is provided for maintaining circuit (l) energized upon completion of reversing. This circuit, it will be recalled, consists of battery |62, conductors 262 and-266, bridging contact 216, contact 218, conductors 286, 21d, solenoid coil 215 of valve |56. This is necessary to permit the low pressure fluid from the governor booster pump to flow through check valve |36, channel 261, valve |56, channel 266 to the upper side of land 2|6 which will keep the governor pilot valve |66 in the down position and maintain the propeller in reverse pitch.

Switch |18 is maintained in the down position by the engagement vof armature 3|6 of solenoid 3|2 engaging the latch 3|4 of armature 3|6 of switch |18. This is necessary to secure during subsequent unreversing a circuit to the. solenoid 2|6 to operate switch |66 and turn motor |66 to drive high pressure pump |56. This is circuit Ll, previously described, which energizes solenoid 326 of switch |16 and maintains switch 334 in the down or contact position. These circuits are shown in Fig. 9.

To unreverse the propeller blades, the switch |12 is moved up (as shown in Fig. 5) causing the bridging contact 216 to contact contacts 342 and 366. Moving bridging contact 216 breaks circuit 1, as previously described, which returns valve |56 to the position shown in Fig. 5. Moving the bridging contact 216 upward establishes av circuit from battery |62 through conductors 282, 264, bridging contact 216, contact 344, conductors 336,'332, switch 336, conductor 336 and solenoid 2|4 to close the circuit to motor |66 for driving the high pressure pump |56. This circuit also interrupts the deicing circuit as previously described. y

The hydraulic functioning is the same as that previously described for feathering. When the blades are in the reverse pitch position, the brush 256 is at the R position of control slip ring 262.

As the blade progresses out of the reverse pitch position towards the constant speed range, the brush will be in contact with a nonconducting insulating segment 346 of control slip ring 262. After the blades, in their unreversing movement, pass LP (low pitch position), the brush 258 will contact conducting segment 343 of control slip ring 262. As this contact is made a circuit from battery |62, conductors 282, tact 216, contact342, conductor 356, solenoid 3|2, conductors 352, 256, brush 256, segment 346 will be established.r `This circuit will energize solenoid 312 retractingarmature 3|6 from the latchv 6M of armature 3|6of switch |16. This will openv previously described circuit l. Opening this circuit will de-energize solenoid 326, releasing switch |16 permitting it to return to the up position as shown in Fig. 5 `and opening the circuit to solenoid 2 I4 which shuts oil` the power to motor |66 and high pressure pumpV |56. This stops the action of the high pressure iiuid and returns thepropeller to normal governor operation.v Switch |22 and its bridging member 216 remain in theirV up position as viewed in Fig. 5 with all circuits cle-energized. l k

It will be evident that asa result of this invention a particularly simple and reliable means has been provided which is entirely automatic for returning the propeller to governor operation following unfeathering and unreversing operation. It will further be evident that the improved means above-described insures that the propeller will be subjected to high pressure uid only during the short timethat 1t is actually required i'or moving the blades in the special purpose ranges. It will also be evident that an excessive electricaldemand will not be imposed upon the airplane electrical system if it cannot accommodate both the deicing system and operation' of the high pressure fluid pump simultaneously by interrupting the former while the latter is operating and only then. It will be further noted that the improved means of this invention for returning the control to the governor, does not require the attention of the pilot during uneathern'ig to release switch iii at the particular time to prevent over'speeding of the engine, as the unfeather means is automatically discontinued when the vpropeller has returned to the governor range. lt will be Iurther noted that the improved means or' this invention lor returning the control to the governor does not require the attention of the pilot during unreversing, ,the only action required of the pilot being the moving of toggle switch v| i2 to the unreverse position to initiate the unreversing operation.

While' several embodiments of the invention have been shown and have been described and illustrated in the accompanying drawings, it will be understood that these particular embodiments of the inventionware `shown for purposes .of illus- 266, bridging con-- tration only and that deviations in the constructin and V'ope'rati'l'l'xl" "o f theinecl'ianism' may' "be iliade without 'departing from the 'spiritl'and'scope of' fthe' invention as llellrled" Vfajlrlpo'rlfled claims. o. l l l, .t Y"What it is ent`is:

*"1. In combination Witha propeller having controllable pitch'bl'des; a "governiflfor 'controlling the pitch of said blades Within a predetermined range, manually 'ntroll'e'd :meansmconnected lv'tll' lsaid governor and said bladesflor 'disabling contrlby' "said 7gol/"erol"'' cfljlrltrl'll "and including means' for' moving'said blades beyond'sa'id4 range and' for returning saidV blades tosaid range and electrically'aotpatedfrnns"connected with sold frianu'allycontrlled means' and said blades and 'controlled by saldfblolde's for automatically als delle e lle gereed. by geen rallnat'icallyreturning-saidprliell' to gov nor control'when said blades 'fpas's into L'said rage from-beyond"saldi-angle?l a 1n' 'combination with a propeller, having Clinrrollololo* -plroh' blades; I@lool-,rlpalfpiropos rorjue-l ieng'saidblades;'meanslor'varfl h offsaid'bladesil'l: a rr'lr'fr'lal'ra electrically Averlergvzfed""lil'lealflsj' I nis'm' vfor moving ksaid? blades beyond "said 'normal range; `a circuit breaker Y*connected lthsfaid aoloor: orlo saldfoleorrlollyojn l automaticallyactuatedf'by 'energize' v* mechanism to `rnai'l'ltain 'said'elect caldeiing 'means"llperatveuvvhle Said electrically l?, I- 'gized means'is'enrgifz'ed. "i f' "`3. combinatioli'a' propeller having variable pltoh blades; 'o' ll'uld operating; pl'torrollonglpg motor therefor,- eleotrloal nl earijs fordeilpgpald blades, a 'governorT controlling vthe""adr'mlflissioil""of lluldtosald motortovorytlleplt sold-blades in a normal operating range of pitchfvailjiation, electrically' lactuated 'meansfor supplyingjll'lid 'to said motor at v'a` pressure liighlr'j than' tle "go 1"'' por oom-rolled'llllldrormylng s one ouro'fa special purposejra ge bevond solo governor 'contro1"'an'ge;"* ircllit'br Connected 'With Said :electrically actuated automatically lnt'rfaptln manvs'lnolllent'toerlerglz actuated 'means to' povidefplt A o ati'ol ofjsaidiloladesinv vsaid special purpose? n) '4t-'ln' coll'lbltlonwlma liropeller'flravln'gbd# trollable 'pitch blll'cles,` a *pitc changing" m or therefor, a""govern'oi vl'lol'lt'roling ic r through' a' normallpitch changing"range.'A e colly omging@ meorsj 'for oorltfollln'g'sold p lfcoll' changingv motor in alspecialpllrplose ge yond` said' normal'r' ri ea ns;- an electrical eiciljl'g' system-"for saldi-blades"'molurllrlg blade elements'carried byfsaid'bladjesj*a` b'ru'sljl c by said propeller andf'aslip 'ijin'gfca ied' by bladerend oontaotlligsaldbrusll a with said"deicin`'elefneiits andsai actuated *means forl transmitting ergy' to saidblade deicing 'elem ling said"electrically actuated sllp` ring haringen lrlsplolcfjely spending t''sai'd-f spcial' rlll'r'l'lllse terrup'ting the' yflovv` f: 'electricalejnergy td' said electrically actuatedlleanl,

5. In combination Withl'apropeller having controllable `pitch blades', electricalblade, "dicifng means 'for deicing said blades; a speed responrsiy governor operatively'connected with said blade for controlling the pitch yofthe blades Within a predetermined range in accordance r'with' speed'.L

' manually controlled el'etrically actuated means f 'on'li'lg'pit'of theheicerciie't,propeller pitch control* means including "eleetrically" 'actuated mechanism for ch'ajl'ihgfthe blade pitclifirl'l said speelal'purpos raggi' l'slllacloll,'ssoolated with said' rln'gpaprrlerl' byj pero blade, forming 'signal creating 'meansfsignal receiving meahsforilng afp'rf ''f Sfaid'piopllei" pitch 'coljltll"lnea'lsQA 4Said brush' and 'slpr'rnfg'f 'IjIIllg a) part' Of v th'ps'igfll transmitting" 'circuit connecting l'said brush' and said signal receiving means and means actuated by' salaY 'signal' 'receiving' moas"'dlsabllg 'solo electrically-'a'ctllatedmechanism; '7."IIr`i"afcntllablepitch"'prpelier having a normal pitchranfg'ald a special purpose "ra-nge and" hayiil'g"ele'ctifical "deiciiig means associated with the propeller lol'aoeegasllp ring oa'rrl'odflsy the blade and a bru'slf cooperating with saidfrlng and forming "partofthedeicercircllit', propeller pitch control meansincld'ng a governor forcolil trolling the blado'pitoh l'rl soldfnorinal-rango 'lld electrically actuated mechanism for 'changinfte blade' pitch "l'n' said special fpllfrpose' range;v said slip ring*havfngmooriduotlhg portions" onse;- lected 'segments'of said ringt forming'signalcreafing "means,v said electrically actuated mechanism incllldiflg'lsiglal receivingme'ans actuated 4by lil'. lerruptlon "or oloo'rrlo'al-JV ourrenft through sold delcri'i'g t0 dee'nig'ie said*'electlc'allyjacfli ated mechanism.

'8.` ac'trollable pitch propeller having a normal pitch rang andaspecial 'purpose range and having 'electrical deicin'g'fxeails associated with 'the' 'propeller' blades, v@slip ring carried by the blade anal-o brush cooperating with solenni; formi'ngpart of'tll doloer'olrou'lt; propellrplloli control-means including :iv governor 'for 'conti-61: llrlg rho'lolado pilolrlnT soldfpolmol-'rong' arid electrically actuated mechanisr'n""f'0r changing the bladel pitch in said specialpllrpose range, said slip nog havlng'llolodnuctlg portions al 'sol lected segmentsY ol?4 said ring forming" -signal orootlpg means-,sola electrically ootuote'd melena anls'lm including Vsignal'ff'lc-eivin'g' Vnfl'ea/nfs: actu-ated py osr'obllsllpg onilootr'lolll current llloligli sld deloer rlngjlto defellr'glz solo` ol'otrloolly" 'ooclli ated meCh'anSm' I E "9@ Inacon'tiollable pitch propeller havingv a normal pitch' range aildfaspeeal' p'poserallge and having 'electrical'` 'deicing "means associated wlthrrhe' propeller pladosfo slip, rllgf4 oarlkl by, the lolo'de and lorusli'oooporotlng. `wlli salti rink @milling Per@ Qf. the ,deier Circuit *propeller pitchA control means inclulilgli"y gol/moi; for controlling the blade pitch'ili said normal rangev'aild eleqtlQeHY actuated lilieiclhalspj fdr llong'pg 'ille'. blade pitch ln sold special purpose roli'fsid slip ring having non-conducting portions at selected segments of said ring forming signal creating means, said electrically actuated mechanism including signal receiving means actuated by interruption of electrical current through said deicer ring to cle-energize said electrically actuated mechanism when. said blades enter said normal pitch range from one direction and actuated by establishing; an electrical current through said deicer ring to rie-energize said electrically actuated mechanism when said blades enter said noru mal range from the other direction.

l0. In combination with a propeller having controllable pitch blades, a pitch changing motor therefor, a governor connected with said motor for controlling the pitch of said blades in the normal range of pitch variation, electrically controlled means connected with said governor and energizable to disable said governor and operate said blades in pitch changing movement beyond said normal range in feather or reverse pitch range, means carried by said blades for making and breaking electrical circuit in said electrically controlled means, means responsive to breaking said circuit for rie-energizing said electrically controlled means, means responsive to making said circuit for dre-energizing said electrically controlled means, and means responsive to deenergizing said electrically controlled means for automatically returning said motor to governor control, said circuit making and breaking means adapted to break a circuit, interrupt said electrically controlied means, and automatically return said motor to said governor control When said blades pass from said feathering range to said normal range, said circuit making land breaking means adapted to make a circuit, interrupt said eiectrically controlled means and automatically return said motor to said governor control incident to passage of said blades from said reverse pitch range to said normal range.

l1. In combination, a propeller having variable pitch blades, a hydraulic pitch changing motor therefor, a governor controlling the admission of fluid to said motor in a normal operating range of pitch variations, a source of fluid pressure, means for selectively connecting said source with said motor to move said blades beyond, and return the blades to, the conveyor control range, pressure responsive means hydraulically connected with said source, other means connecting said pressure responsive mean and said source for controlling said fluid pressure source, electrical means operatively connected with said source for controlling said huid pressure source, means for creating a pressure surge in said fluid from said source to actuate said pressure responsive means and disable said source when said propeller blades reach feathered position and reversed position means actuated by movement of said blades for operating said electrical means and automatically disabling said source incident to movement of said propeller blades from feathered position and reverse position to said operating range.

l2. lin combination, a propeller having variable pitch blades, a hydraulic pitch changing motor therefor, an electrical means for deicing said blades, a governor controlling the admission of fluid to said motor in a normal operating range of pitch variation, a source of fluid pressure, means for connecting said motor with said source for operating said motor to move said blades beyond the governor control range, pressure responsive means connected with said source for controlling said uid pressure source, a second electrical means connected with said source for controlling said fluid pressure source, means for creating a pressure surge in said fluid from said source to actuate said pressure responsive means and 'disable said source When said propeller blades reach feathered position and reversed position and means responsive to movement of said propeller blades 4from feathered position and reverse position to said operating range for automatically actuatingl said second electrical means to disable said source, 4and means responsive to operation of 'the pitch changing motor to move said blades'to feathered position and reversed position and responsive to operation of the pitch changing motor to move said blades from feathered and reversed position to said normal operating range for automatically interrupting the flow of electricity to said electrical deicing means.

13. In combination with a propeller having controllable pitch blades, a pitch changing motor therefor, a governor controlling said motor in a normal range of pitch change, electrically controlled means for operating said motor beyond said range into and out of reverse pitch, a slip ring carried by said blade, a brush carried by said propeller contacting said slip ring, said slip ring having an insulated segment corresponding to reverse pitch range, manually actuated control means for energizing said electrically controlled means to move said blades to reverse pitch position, manually actuated means to initially energize said electrically controlled means to move said blades from reverse pitch position toward said normal range, an electrically actuated circuit breaker for breaking the circuit to said electrically ccntrolled means, said circuit breaker being actuated upon contact of said brush with the uninsulated portion of said slip ring, said insulated segment maintaining said circuit breaker inoperative by insulating said brush from said slip ring during a selected blade pitch range, and said circuit breaker being actuated to interrupt said electrically controlled means when said brush no longer contacts said insulating segment.

14. In combination, a propeller having variable pitch blades, a hydraulic pitch changing motor therefor, a governor controlling the admission of fluid to said motor in a normal operating range of pitch variation, a source of fluid pressure means connecting said source with said motor for operating said motor to move said blades beyond said governor controlled range in feathered and reverse pitch ranges, electrical control means for controlling said fluid pressure source, means actuated incident to movement of said blades to feathered and reverse pitch positions for automatically actuating said electrical control means to render said source ineffective to change blade pitch when said blades have been moved by said motor to feathered position and reverse pitch position and means actuated incident to return of said blades to normal position for automatically actuating said electrical control means to render said source ineffective to change blade pitch when in the unfeathering movement and unreversing movement said blades reach predetermined positions in the normal governor controlled pitch range.

15. In a control for a controllable pitch propeller blade comprising a hydraulically actuated pitch changing motor, a source of fluid supply, a governor having a governor valve for controlling the now of fluid from said fluid supply to said motor to maintain substantially constant yruiopeller speed; governor valve movingY means connected with4 said governor valve,v a4 second source of' ud supply mclud'ing an electrically actuated pump, electrically actuated valve means for directing fluid from said second' sourceY to said governor valve movngmeansl to selectively move said governor valve to direct fluid'jfrom said second source to one. side or thevother. of said motor, a slip ringhaving conducting and insu lating portions, and movable in timed. Arelation withv said blade, a switch and connections for completing the electrical' circuit' to safdlectri' cally actuated pump, including a connection through said slip ring; sad insulated' Vportion breaking saldi connections, and'v stopping, said pump when the blade reaches.: apredetermined position., Y

CAIVIN'D.

Refcrences'ci in the le of this patent UNITED STATES PATENTS Number;

Name Date Mullen Aug. 25, 1942 Beebe Nov. 9, 1943 Chillson Apr. 4, 1944 Martin June 11, 1946 Poekel June 25, 1946 Forsyth Mar. 2, 1948 Eaton July, 6, 1948 

